Effects of traditional Chinese medicine colquhounia root tablet on the expression of tight junction protein ;claudin-2 and ZO-1 in bronchial epithelium tissue of rats with acute lung injury induced by oleic acid / 中华危重病急救医学

ABSTRACT

Objective To investigate the effects of traditional Chinese medicine colquhounia root tablet on the expression of tight junction protein claudin-2 and ZO-1 in bronchial epithelium tissues of rats with acute lung injury (ALI), and to study the mechanism of protective effect of colquhounia root tablet on ALI. Methods Twenty-four healthy male Sprague-Dawley (SD) rats were randomly divided into control group, ALI group and colquhounia root tablet pretreatment group, with 8 rats in each group. The model of ALI was reproduced by intravenous injection of oleic acid 0.04 mL/kg, and the rats in cont rol group were given the same amount of normal saline (NS) instead. The rats in colquhounia root tablet pretreatment group were intragastric administrated with colquhounia root tablet of 600 mg·kg-1·d-1 (2 mL) for 10 days before model reproduction, and the rats in control group and ALI group were given the same amount of NS. At 4 hours after model reproduction, the blood was drawn from abdominal aorta, and bronchoalveolar lavage fluid (BALF) was collected for determination of protein content in plasma and BALF, and the lung permeability index (LPI) was calculated. The rats were sacrificed to collect lung tissues for determination of lung wet/dry weight ratio (W/D), the changes in pathology of lung tissue were observed after hematoxylin and eosin (HE) staining with light microscope, and lung injury score (LIS) was evaluated. The immunohistochemic al staining was used to detect the expression and localization of claudin-2 and ZO-1 in bronchial epithelium tissues. The protein expressions of claudin-2 and ZO-1 in bronchial epithelium tissues were determined by Western Blot. Results Compared with control group, the lung injury in ALI group was more obvious including cellular edema and structural disorder of intercellular connection by optical microscope, and LIS, W/D ratio, and LPI were significantly increased (LIS 3.81±0.42 vs. 0.40±0.08, W/D 7.68±0.64 vs. 4.44±0.39, LPI 0.89±0.15 vs. 0.38±0.05, all P < 0.01). Claudin-2 and ZO-1 were mainly expressed in the bronchial epithelium cell, and the expression degrees were significantly weakened in ALI group as compared with control group. It was shown by Western Blot results that compared with control group, the protein expressions of claudin-2 and ZO-1 were significantly down-regulated in ALI group [claudin-2 protein (gray value) 0.43±0.31 vs. 2.16±1.33, ZO-1 protein (gray value) 1.25±0.41 vs. 2.82±0.76, both P < 0.01]. Compared with ALI group, colquhounia root pretreatment could effectively diminish the degree of ALI (LIS 1.22±0.39 vs. 3.81±0.42, W/D 4.62±0.84 vs. 7.68±0.64, LPI 0.46±0.07 vs. 0.89±0.15, all P < 0.01), and the protein expressions of claudin-2 and ZO-1 were significantly up-regulated [claudin-2 protein (gray value) 2.98±0.91 vs. 0.43±0.31, ZO-1 protein (gray value) 2.35±0.51 vs. 1.25±0.41, both P < 0.01]. Conclusion Administration of colquhounia root table could attenuate lung injury induced by oleic acid with improving epithelial barrier function via up-regulate the expression claudin-2 and ZO-1, which play a protective effect on the lung of rats with ALI.